HK1194489A - Fastening of a dial to a timepiece bottom plate - Google Patents

Description

Fastening of a dial to a timepiece bottom plate

Technical Field

The invention concerns a timepiece assembly comprising at least one bottom plate and at least one dial, arranged to be fixed one on top of the other, the timepiece assembly comprising a plurality of centring pins integral with said bottom plate or said dial, each centring pin being arranged to cooperate with an elongated slot in said dial or said bottom plate with radial and tangential play for the relative positioning of said at least one dial with respect to said at least one bottom plate, said timepiece assembly further comprising retaining means integral with said bottom plate or said dial, said retaining means being arranged to cooperate with complementary retaining means integral with said dial or said bottom plate, said retaining means and/or said complementary retaining means comprising elastic return means for pressing said at least one dial against said at least one bottom plate, wherein the resilient return means has a substantially tangential movability in a plane perpendicular to a radial line connecting the centre of the base plate and the resilient return means and perpendicular to the plane of the base plate.

The invention also relates to a timepiece comprising at least one such timepiece component.

The present invention relates to the field of horology, and more specifically to the field of assembling a dial onto a bottom plate of a watch.

Background

When the bottom plate and the dial are made of different materials, they are subjected to different degrees of expansion because the coefficients of expansion of their materials are different. Thus, a dial fixed to the base plate and generally having a thickness much smaller than that of the base plate can bend or contract with temperature changes. In some severe cases, especially at high temperatures, for example in tropical or desert regions, such deformations may cause the hands to come out, which makes the watch unsuitable for use.

CH patent application No120846A in the name of BOVET fres discloses the use of clips that cooperate with pins to secure a dial to a base plate. US patent application No.543628A in the name of MARSH discloses a similar arrangement.

CH patent application No.82809A in the name of WILLIAMSON discloses a device for fixing a dial with a foot by gripping the dial foot, which is received in the cavity of a slot in a stamped bottom plate by angular folding of radial fingers contained in said bottom plate.

CH patent application No.125760 in the name of GAERTNER discloses the fixing of a dial having a foot by elastic retention of the foot, which is achieved by using a spring flange held by a screw.

Disclosure of Invention

The invention proposes to ensure the retention of the dial and its geometry (generally its flatness) regardless of the differences in the degree of expansion of the members of the dial.

The invention also proposes to provide a simple method for fixing a dial to a base plate without the need to pre-machine the dial, in particular without the need to pre-machine its periphery.

The invention therefore concerns a timepiece assembly comprising at least one bottom plate and at least one dial, arranged to be fixed one on top of the other, the timepiece assembly comprising a plurality of centring pins integral with said bottom plate or said dial, each centring pin being arranged to cooperate with an elongated slot in said dial or said bottom plate with radial and tangential clearances for the relative positioning of said at least one dial with respect to said at least one bottom plate, said timepiece assembly further comprising retaining means integral with said bottom plate or said dial, said retaining means being arranged to cooperate with complementary retaining means integral with said dial or said bottom plate, said retaining means and/or said complementary retaining means comprising elastic return means for pressing said at least one dial against said at least one bottom plate, wherein said elastic return means have a substantially tangential movability along a plane perpendicular to a radial line connecting the centre of said bottom plate and said elastic return means and to a plane of said bottom plate, characterized in that said retaining means and/or said complementary retaining means carrying said elastic return means comprise at least one elastic clip lug projecting in a cantilevered manner with respect to said dial or said bottom plate in a direction substantially perpendicular to the plane of said dial or said bottom plate, said lug comprising a head having a return stop surface for reciprocal abutting cooperation with a complementary stop surface comprised in said bottom plate or said dial.

The invention also relates to a timepiece comprising at least one such timepiece component.

Drawings

Other features and advantages of the present invention will become more apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings, in which:

fig. 1 shows a schematic top view of a timepiece assembly according to the invention, having a base plate on which a dial is mounted, said dial being centred by a centring pin and kept pressed against said base plate with a tangential clearance by elastic return means.

Figure 2 shows a schematic perspective view of the assembly of figure 1.

Figure 3 shows a schematic perspective view of a detail of the elastic return means for pressing the assembly, shown at reference E in figure 2.

Fig. 4 shows a schematic top view of a detail of the positioning of the centering pin in the elongated slot, shown at reference sign a in fig. 1.

Fig. 5 shows a schematic cross-section of a detail of the positioning of the centering pin in the elongated slot, shown at reference BB in fig. 1, in a plane perpendicular to the plane of the base plate.

Fig. 6 shows a schematic top view of a detail of the mutual cooperation between the elastic return means, which are located in the radial slots and are used to press the assembly together, and the bearing surface of the dial, shown at C in fig. 1.

Fig. 7 shows a schematic cross-section, in a plane tangential to the bottom plate, of a detail of the mutual cooperation between the elastic return means, which are located in the radial slots and are used to press the assembly together, and the bearing surface of the dial, shown at DD in fig. 1.

Fig. 8 shows a block diagram of a timepiece comprising a timepiece assembly according to the invention.

Detailed Description

The present invention relates to the field of horology, and more specifically to the field of assembling a dial onto a bottom plate of a watch.

The invention relates more particularly to a timepiece assembly 100, this timepiece assembly 100 comprising:

-at least one bottom plate 1;

at least one dial 2, arranged to be fixed one above the other;

a plurality of centring pins 3 integral with the bottom plate 1 or the dial 2, each centring pin being arranged to cooperate with an elongated slot 4 in the dial 2 or the bottom plate 1 with radial and tangential clearances for the relative positioning of at least one dial 2 with respect to at least one bottom plate 1.

The assembly 100 also comprises a retaining device 5 integral with the bottom plate 1 or with the dial 2, the retaining device 5 being arranged to cooperate with a complementary retaining device 6. The complementary retaining means 6 are integral with the dial 2 or the bottom plate 1.

The retaining means 5 and/or the complementary retaining means 6 comprise elastic return means 7 for pressing at least one dial 2 against at least one bottom plate 1.

According to the invention, as shown in figures 1, 2, 3, 6 and 8, the elastic return means 7 have a substantially tangential movability in a plane PT perpendicular to a radial line R connecting the centre O of the base plate 2 and the elastic return means 7 and to the plane P of the base plate 2.

The tangential movability means that deformations of the dial 2 or of the base plate 1 can occur as a result of thermal stresses.

The invention is more particularly shown for the case where the pin 3 and the retaining means 5 are integral with the base plate 1. The skilled person knows how to form the opposite structure, i.e. that these elements are integral with the dial 2; it is also known how to form a hybrid structure, i.e. pin 3 integral with bottom plate 1 and retaining means 5 integral with dial 2, or pin 3 integral with dial 2 and retaining means 5 integral with bottom plate 1.

Preferably, as shown in figures 1, 4 and 8, the elongated slot 4 is substantially radially oriented with respect to an axis D which is substantially at the centre O of the soleplate 1 and perpendicular to the plane P of the soleplate 1. The dial 2 can thus expand and contract radially on the bottom plate 1, while still being oriented by the pin 3 in the elongated slot 4 and retained axially by the retaining means 5, which retaining means 5 are advantageously formed by a clip.

Advantageously, a plurality of pins 3 are used to determine the direction of the dial. Preferably, one of the pins 3 is used to centre the position of the dial, the other pins being designed with greater clearance from the respective slots 4 to provide guidance.

Preferably, for the first centering pin 3 used for centering, the first tangential gap JT1 between said first centering pin 3 and the first elongated slot 4 associated therewith is smaller than the tangential gaps JT between each of the other centering pins 3 and the elongated slot 4 associated therewith.

The slot 4 of the first centring pin can also be reduced to a simple hole, in which case the first pin 3 acts as a pivot for the dial 2 with respect to the bottom plate 1.

However, in the particular embodiment illustrated in the figures, at least one of said elongated slots 4 is an open through slot, and preferably all elongated slots 4 are open through slots, to allow the dial to deform during thermal expansion.

Preferably, the radial clearance JR1 between said first centring pin 3 and the first elongated slot 4 associated therewith is greater than or equal to the maximum radial clearance between the bottom plate 1 and the dial 2.

In the embodiment shown in the figures, the retaining means 5 is made in the form of a clip lug or clip. Thus, the retaining means 5 and/or the complementary retaining means 6 carrying the elastic return means 7 comprise at least one elastic clip lug 8, which clip lug 8 projects in a cantilevered manner with respect to the dial 2 or the bottom plate 1 in a direction substantially perpendicular to the plane of the dial 2 or the bottom plate 1.

The lug 8 has a head 9, the head 9 having a return stop surface 11, the return stop surface 11 being arranged to cooperate mutually abuttingly with a complementary stop plane 12 comprised in the bottom plate 1 or in the dial 2.

Preferably, each lug 8 is movable within a radial recess 13 substantially in the radial direction of the bottom plate 1 or dial 3, with a radial clearance at least equal to the maximum thermal clearance between the bottom plate 1 and the dial 2.

In a particular embodiment, as shown in the figures, at least one of said radial recesses 13 is an open through recess.

Advantageously, the dial 2 is a blank cut dial (cut blank dial).

The invention also relates to a timepiece 1000 including at least one such timepiece assembly 100.

The invention ensures that the dial is properly retained on the base plate, regardless of the operating temperature of the watch. Thus, the different expansions of the dial and the bottom plate are no longer critical.

The invention also reduces the manufacturing costs of the dial, which does not require injection or preliminary machining, but can be used directly after cutting, for example in the form of a cut sheet.

The components are simple and inexpensive to assemble because the clamping system does not require any special equipment.

The method of retaining the dial on the base plate means that, during the watch manufacturing phase, the pre-assembled assembly can be turned over thanks to the fixed retention provided by the elastic retaining lugs.

Since screws, adhesives, or the like are not used, the assembly time is shortened.

Claims (9)

1. Timepiece assembly (100), the timepiece assembly (100) comprising at least one bottom plate (1) and at least one dial (2) arranged to be fixed one on top of the other, the timepiece assembly (100) comprising a plurality of centring pins (3) integral with the bottom plate (1) or the dial (2), each centring pin (3) being arranged to cooperate with an elongated slot (4) in the dial (2) or the bottom plate (1) with radial and tangential clearances for the relative positioning of the at least one dial (2) with respect to the at least one bottom plate (1), the timepiece assembly (100) further comprising a retaining means (5) integral with the bottom plate (1) or the dial (2), the retaining means (5) being arranged to cooperate with complementary retaining means (6), the complementary retaining means (6) being integral with the dial (2) or the bottom plate (1), said retaining means (5) and/or said complementary retaining means (6) comprising elastic return means (7) for pressing said at least one dial (2) against said at least one bottom plate (1), wherein said elastic return means (7) have a substantially tangential mobility along a Plane (PT) perpendicular to a radial line (R) connecting the centre of said bottom plate (1) and to a plane (P) of said bottom plate (1), characterized in that said retaining means (5) and/or said complementary retaining means (6) carrying said elastic return means (7) comprise at least one elastic clip lug (8), which elastic clip lug (8) projects in a cantilevered manner with respect to said dial (2) or said bottom plate (1) in a direction substantially perpendicular to the plane of said dial (2) or said bottom plate (1), said lug (8) comprises a head (9), the head (9) having a return stop surface (11), the return stop surface (11) being intended to cooperate mutually abuttingly with a complementary stop surface (12) contained in said bottom plate (1) or in said dial (2).

2. Timepiece assembly (100) according to claim 1, wherein the elongated slot (4) is substantially radially oriented with respect to an axis (D) substantially at the centre (O) of the bottom plate (1) and perpendicular to the plane (P) of the bottom plate (1).

3. Timepiece assembly (100) according to claim 1, wherein a first tangential gap (JT 1) between a first of said centering pins (3) and a first of said elongated slots (4) associated therewith is smaller than a tangential gap (JT) between each of the other pins (3) and the elongated slots (4) associated therewith.

4. Timepiece assembly (100) according to claim 1, wherein the radial clearance (JR 1) between a first of said centering pins (3) and the first of said oblong slots (4) associated therewith is greater than or equal to the maximum radial thermal clearance between said bottom plate (1) and said dial (2).

5. Timepiece assembly (100) according to claim 1, wherein at least one of the elongated slots (4) is a through slot.

6. Timepiece assembly (100) according to claim 1, wherein each lug (8) is movable in a radial recess (13) substantially in the radial direction of the bottom plate (1) or the dial (2) with a radial clearance at least equal to the maximum thermal clearance between the bottom plate (1) and the dial (2).

7. Timepiece assembly (100) according to claim 6, wherein at least one of the radial notches (13) is a through notch.

8. The timepiece assembly (100) according to claim 1, wherein the dial (2) is a blank cut dial.

9. Timepiece (1000) comprising at least one timepiece assembly (100) according to claim 1.